Nirsevimab
Nirsevimab is a monoclonal antibody used to prevent RSV (Respiratory Syncytial Virus) lower respiratory tract disease in newborns, infants, and young children up to 24 months old.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Nirsevimab: Patient Information Guide
A plain-language walkthrough of Nirsevimab — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Nirsevimab (brand name Beyfortus) is approved to prevent RSV (Respiratory Syncytial Virus) lower respiratory tract disease in young children. Specific approved uses include:
- Beyfortus is used to prevent RSV lower respiratory tract disease in newborns and infants born during or entering their first RSV season
- Beyfortus is used to prevent severe RSV disease in children up to 24 months of age who remain vulnerable through their second RSV season — including children with chronic lung disease (CLD) of prematurity or hemodynamically significant congenital heart disease (CHD)
- Beyfortus has also been studied in children up to 24 months of age with immune-compromising conditions, with a consistent safety profile
⚙️How it works▾
Nirsevimab is a monoclonal antibody — a targeted, lab-made protein designed to fight a specific threat. It binds to a site on the RSV virus called the F (fusion) protein, which is the part the virus uses to latch onto and enter the cells lining your child's airways and lungs. By blocking this step, nirsevimab stops RSV from causing infection in the lower respiratory tract. A single dose provides protection lasting approximately 5 months based on clinical data.
Resistance to nirsevimab can occur if the RSV virus develops changes (mutations) in its F protein binding site. Large resistance-causing changes were rare in historical RSV samples and remain uncommon, though some variants with reduced susceptibility have been identified; their real-world impact is not yet fully known.
💊How it's taken▾
Beyfortus is given as a single intramuscular (IM) injection by a healthcare provider — typically into the outer thigh. The dose depends on the child's body weight and which RSV season they are entering.
- For the first RSV season: one injection, with the size based on body weight
- For the second RSV season (children at increased risk): two injections given at the same visit, at two different sites
- Children undergoing heart surgery with cardiopulmonary bypass may need an additional dose after surgery — the timing determines the dose; discuss with your child's provider
There is no oral form of this medication. Always follow your child's healthcare provider's instructions on when to schedule the injection relative to RSV season.
🤒Side effects — in detail▾
Beyfortus is generally well tolerated — most children who received it in clinical trials had no adverse reactions.
- Rash (occurring within 14 days of the injection) — reported in about 1 in 100 children
- Injection site reaction — pain, redness, swelling, or induration (firmness) at the shot site, reported in about 3 in 1,000 children
Serious allergic reactions, including anaphylaxis (a severe, whole-body allergic response), have been reported. Seek emergency medical help immediately if your child develops hives, trouble breathing, bluish skin, or sudden limpness after the injection.
⚠️Warnings & precautions▾
- Serious allergic reactions / anaphylaxis: Reactions including hives, breathing difficulty, bluish skin (cyanosis), and sudden limpness (hypotonia) have been reported after Beyfortus. Children should be monitored for at least 60 minutes post-injection. Emergency treatment should be on hand.
- Bleeding risk with injections: Because this is a muscle injection, use extra caution in children with thrombocytopenia (low platelet count), coagulation (clotting) disorders, or those taking anticoagulant (blood-thinning) medications.
- Not a treatment for active RSV: Beyfortus prevents RSV disease — it does not treat an infection that is already present.
- Not for children over 24 months: Safety and effectiveness have not been established in children older than 24 months of age.
🔀What it interacts with▾
Nirsevimab has a small number of notable interactions to be aware of:
- Childhood vaccines: Beyfortus can be given at the same visit as routine vaccines, but must always use a separate syringe at a different injection site — never mixed together
- Palivizumab (Synagis): Do not give palivizumab to a child who has already received Beyfortus in the same RSV season; however, Beyfortus may be used in a subsequent RSV season in children who previously received palivizumab
- Other immunoglobulin products: There is no available data on co-administering Beyfortus with other immunoglobulin medications — consult your provider
- RSV diagnostic tests: Beyfortus does not interfere with standard RT-PCR or rapid antigen RSV tests; if a test is negative but RSV is strongly suspected, an RT-PCR test is recommended to confirm
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Serious allergy history: Beyfortus is contraindicated (must not be given) in children with a history of serious allergic reactions, including anaphylaxis, to nirsevimab-alip or any ingredient in the product
- Bleeding or clotting conditions: Tell your provider if your child has a bleeding disorder, low platelets (thrombocytopenia), or takes blood-thinning medication
- Age limit: Beyfortus is not approved for children older than 24 months — safety and effectiveness are not established in that age group
- Heart surgery: Children who need cardiac surgery with cardiopulmonary bypass may require an additional dose after surgery; discuss the plan with your child's care team before and after any procedure
- Not for adults or reproductive-age individuals: Beyfortus is not indicated for adults, and is not for use in pregnant or breastfeeding individuals
- Immune-compromised children: Beyfortus has been studied in children with a variety of immune-compromising conditions; the safety profile was consistent with other trials, but discuss your child's specific situation with their provider
🚑If you take too much▾
There is limited experience with Beyfortus overdose. There is no specific antidote or reversal treatment. If an overdose is suspected, the child should be monitored by healthcare providers for any adverse reactions, and supportive care should be provided as needed.
📡Pharmacodynamics — effects in the body▾
Nirsevimab works by raising RSV-neutralizing antibody levels in the bloodstream, which helps the body block RSV before it can cause a lower respiratory tract infection. Higher drug exposure in the blood is linked to a lower chance of a medically attended RSV lung infection. Based on clinical data, a single dose of Beyfortus provides protection that extends through approximately 5 months.
🔬Pharmacokinetics — how your body processes it▾
After an intramuscular injection, about 84% of nirsevimab is absorbed into the bloodstream, with peak levels typically reached around day 6. The drug has a long half-life of approximately 71 days, meaning it stays active in the body for several months after just one dose. Nirsevimab is broken down by the body's natural protein-recycling pathways into small peptides (protein fragments) and does not rely on the liver or kidneys for elimination in the traditional sense.
📦How to store it▾
Store refrigerated between 36°F to 46°F (2°C to 8°C). refrigerator, BEYFORTUS must be used within 48 hours or discarded. Store BEYFORTUS in original carton to protect from light until time of use.
📄 Written from Nirsevimab’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Nirsevimab — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Beyfortus and why does my baby need it? ▾
How is it given, and will it hurt my baby? ▾
Are there any serious side effects I should watch for at home? ▾
Can Beyfortus be given at the same time as my baby's other vaccines? ▾
Does my baby need more than one dose? ▾
If my baby already got palivizumab (Synagis), can they still get Beyfortus? ▾
Is Nirsevimab available over the counter? ▾
When was Nirsevimab first available? ▾
Who makes Nirsevimab? ▾
💬 Answers drafted from Nirsevimab’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Nirsevimab comes
Nirsevimab is available in 2 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Injection
How this form is used
- Beyfortus injection is used to prevent RSV lower respiratory tract disease in newborns and infants born during or entering their first RSV season
- Beyfortus injection is used to prevent severe RSV disease in children up to 24 months of age who remain vulnerable through their second RSV season
- Beyfortus must be administered by a healthcare provider as an intramuscular (IM) injection, preferably into the outer thigh — never the buttock
- Beyfortus comes in two pre-filled syringe sizes (50 mg with a purple plunger, and 100 mg with a light blue plunger) — the correct size is chosen based on the child's body weight and RSV season
- If two injections are required (second RSV season dosing), each Beyfortus injection must be given at a different injection site
- Beyfortus should not be used if the solution is cloudy, discolored, or contains particles, or if the syringe has been dropped or damaged
Oral solution
📊 Nirsevimab across the U.S. market
How Nirsevimab appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
🔍 Compare Nirsevimab products
A representative set of FDA-listed product records for Nirsevimab — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 50 mg/0.5 mL | — | Novo Nordisk Production Belgium SA × 2 listings | DRUG FOR FURTHER PROCESSING | View NDC → |
| 100 mg/mL | — | Novo Nordisk Production Belgium SA × 2 listings | DRUG FOR FURTHER PROCESSING | View NDC → |
| 50 mg/0.5 mL | — | Patheon Manufacturing Services LLC | DRUG FOR FURTHER PROCESSING | View NDC → |
| 100 mg/mL | — | Patheon Manufacturing Services LLC × 3 listings | DRUG FOR FURTHER PROCESSING | View NDC → |
| 50 mg/0.5 mL | Intramuscular | Sanofi Pasteur Inc. | BLA | View NDC → |
| 100 mg/mL | Intramuscular | Sanofi Pasteur Inc. | BLA | View NDC → |
| 100 mg/mL | Intramuscular | Sanofi Vaccines US Inc. × 6 listings | BLA | View NDC → |
| 💊Oral solution | ||||
| 20 kg/20 kg | — | SAMSUNG BIOLOGICS Co., Ltd. | BULK INGREDIENT | View NDC → |
Showing 17 of 17 products — FDA National Drug Code Directory. See every product, package size and price: browse all 17 Nirsevimab NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Nirsevimab — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Nirsevimab in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Nirsevimab went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 2642401 1 dose form · 2 strengths
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Dose form (SCDF) Prefilled Syringe RxCUI 2642405No current FDA listingClinical drug / strength (SCD) 0.5 ML nirsevimab-alip 100 MG/MLRxCUI 26424061 ML nirsevimab-alip 100 MG/MLRxCUI 2642414
Look up RxCUI 2642401 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Nirsevimab is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Nirsevimab belongs to the Respiratory Syncytial Virus Anti-F Protein Monoclonal Antibody class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Sanofi Pasteur Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.